Antibiotics are required early in sepsis. However, in the era of antibiotic stewardship, ensuring an accurate diagnosis is often the cornerstone of providing proper care. After an overview of the SIRS criteria and sepsis markers, this presentation reviews common and uncommon sepsis imposters (e.g., atelectasis, malignant hyperthermia, and serotonin syndrome). A full discussion of the labs and diagnostics needed to distinguish between true sepsis and its imitators is included. By the end of the presentation, the learner will have broadened their differential diagnosis of sepsis and improved their diagnostic accuracy.